716 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



accounts so beautifully for so many of the celestial phenomena, and 

 still clino; to old hypotheses, which account for nothing without 

 doino" violence to the principles of modern science. Wiser heads 

 mav yet, and very soon, account rationally for what to us now 

 seems mysterious. 



The admirable doctrine of correlation, conservation and conver- 

 sion of forces must not be overlooked, and ours is the only theory 

 that can harmonize with it and carry us back to a consistent 

 bec;innino" of the present order. Some better and more rational 

 theory than has ever yet been sought out must be oflered before 

 we can yield up this. 



We find strong support in the remarkable relation which exists 

 in the times, distances and movements of the planets; showing a 

 complete family connection an;ong them. The distances have been 

 set forth in other papers. For the tunes of rotation Kepler 

 demonstrated that "The squares of the times of the revolutions 

 are, to each other, as the cubes of their mean distances." It would 

 seem by this that Mercury is the last planet that can be thrown 

 oflf. 



Let us now direct our attention to the sun and his sources of 

 heat. Condensation always develop^es heat. The falling together 

 of matter produces heat. The matter of our solar system which 

 has not gone to form planets, satellites, comets or meteorites, has 

 fallen into the domain of the sun ; and the matter which has fallen, 

 OS well as that upon which it has fallen, has become heated by the 

 concussion and pressure. But these are not the only sources of 

 heat to the sun. As the molecules of matter have approached 

 each other, they have slowly and gradually come within the sphere 

 of chemical attraction, whose action, in combining chemically the 

 elements of matter, is by far the greatest source of free heat of 

 any and all others combined. This fact may be illustrated many 

 ways. Witness the burning of gas, and in combustion of all kinds. 

 Observe the combination of oxygen with a metal, for instance, on 

 heatins: these few o-rains of Maijnesium. It is one of the liijhtest 

 metals, yet its chemical relations are such as to develop intense 

 light and heat in burning. In this we have true solar light and 

 heat, which has been carefully conserved, stored up and handed 

 down to us for our amusement and instruction this evening. It 

 was once a part of the sun ; it is now an integral of the earth, and 

 the earth was once an integral of the sun. It was a favorite idea 

 of Mr. George Stephenson that the light which wc nightly obtain 



